High-intensity decreasing interval training (HIDIT) increases time above 90% O₂peak

Training near $$O₂max is considered to be the most effective way to enhance $$O₂max. High-intensity interval training (HIIT) is a well-known time-efficient training method for improving cardiorespiratory and metabolic function and $$O₂max. While long HIIT bouts allow $$O₂max to be achieved quickly, short HIIT bouts improve time to exhaustion (Tlim). The aim of this study was to evaluate the time spent above 90% $$O₂peak (T > 90% $$O₂peak) during three different HIIT protocols.

Twelve cyclists performed three HIIT sessions. Each protocol had the same work and recovery power and ratio of work·recovery^-1. The protocols consisted of long-interval HIIT (LI_HIIT, 3 min work-2 min recovery), short-interval HIIT (SI_HIIT, 30 s work-20 s recovery), and high-intensity decreasing interval training (HIDIT, work from 3 min to 30 s and recovery from 2 min to 20 s). T > 90% $$O₂peak, Tlim, blood lactate [La], and rate of perceived exertion (RPE) were measured at Tlim.

T > 90% $$O₂peak was greater in HIDIT (312 ± 207 s) than in SI_HIIT (182 ± 225 s; P = 0.036) or LI_HIIT (179 ± 145 s; P = 0.027). Tlim was not significantly different (P > 0.05) between HIDIT (798 ± 185 s), SI_HIIT (714 ± 265 s), and LI_HIIT (664 ± 282). At Tlim, no differences in [La] and RPE were found between protocols (P > 0.05).

HIDIT showed the highest T > 90% $$O₂peak, suggesting that it may be a good strategy to increase time close to $$O₂peak, despite similar Tlim, [La], and RPE at Tlim.